Experts recommend devoting up to 5 percent of your fixed-income portfolio to high-yield bonds, according to The Wall Street Journal.

"Holding both investment-grade and junk-bond funds is a better idea [than holding junk alone], and makes it less likely you'll be thrown off a cliff if junk bonds lose favor for an extended period," writes Journal reporter John Wasick.

To be sure, junk bonds often perform better than Treasurys when interest rates rise. That's because rising rates generally signify the economy is doing well. And when the economy is doing well, fewer companies tend to default on their bonds.

Meanwhile, a sharp run-up in junk bond yields can indicate trouble ahead for stocks. "High-yield is the first sign you have that something could be wrong," investment consultant Komal Sri-Kumar told The New York Times.

"It doesn’t have to give rise to a 2008 type of collapse, but it tells you there is excess liquidity in the system."

While easy credit has been the rule of the last few years, "at some point a switch goes off, and people say it can’t go on forever," he said.